1. Field of the Invention
The present disclosure relates to a process cartridge, an electrophotographic image forming apparatus using the process cartridge, and an assembly method of the process cartridge.
The electrophotographic image forming apparatus forms an image on a recording medium by using an electrophotographic image forming system. The electrophotographic image forming apparatus may be, for example, an electrophotographic copier, a laser beam printer, a LED printer, or a facsimile apparatus.
The process cartridge has a cartridge, in which an electrophotographic photosensitive member and a process unit that acts on the electrophotographic photosensitive member are integrated, and which is removably mounted on an apparatus body of the electrophotographic image forming apparatus.
2. Description of the Related Art
There has been typically known a process cartridge in which a developing unit including a developing roller as a developing device is rotatably coupled with a photosensitive unit including a photosensitive drum as an electrophotographic photosensitive member by a coupling member. In this process cartridge, the developing unit is urged to the photosensitive unit by the weight of the developing unit or an urging member such as a spring. Hence, the developing roller in the developing unit can be stably urged to the photosensitive drum in the photosensitive unit. A developing system used in the electrophotographic image forming apparatus includes a non-contact developing system in which a very small gap is provided between the surface of the developing roller and the surface of the photosensitive drum. In the non-contact developing system, gap retaining members are provided at both ends of the developing roller, and the developing roller comes into contact with the photosensitive drum through the gap retaining members. Since the gap retaining members retain a constant gap between the surface of the developing roller and the surface of the photosensitive drum, the electrophotographic image forming apparatus can stably output a good image.
However, alignment between the rotation axis of the developing roller and the rotation axis of the photosensitive drum may be deviated from an intended relationship, for example, because the dimensions or assembly positions of respective members used for the process cartridge have errors or an impact is applied to the process cartridge and hence the process cartridge is deformed. At this time, a contact pressure of the developing roller with respect to the photosensitive drum at one end in an axial direction of the developing roller may be markedly smaller than a contact pressure of the developing roller at the other end, and the one end side of the developing roller may be separated from the photosensitive drum (hereinafter, referred to as one-side contact). To correct the one-side contact of the developing roller, a large urging force has to be applied to the one end side of the developing roller.
There is known the following method as a method of stably urging the developing roller to the photosensitive drum.
Japanese Patent Laid-Open No. 8-339149 describes a method of fitting a shaft that rotatably couples the developing unit with the photosensitive unit to a long hole at the one end side in the longitudinal direction of the process cartridge. If a gap is generated between the shaft and the long hole, the coupling position of the developing unit and the photosensitive unit can be moved. This movement absorbs the errors of the dimensions of the respective members of the process cartridge. Hence the developing roller is stably urged to the photosensitive drum.